GEUS Bulletin 2021-03-05T08:36:43-08:00 Catherine Jex Open Journal Systems <p>GEUS Bulletin (eISSN: 2597-2154) is the current flagship journal published by the&nbsp;<a href="" target="_blank" rel="noopener">Geological Survey of Denmark and Greenland (GEUS)</a>. Previously, the Geological Survey of Denmark and Greenland Bulletin (eISSN: 1904-4666).&nbsp;We are peer-reviewed and open access. GEUS Bulletin publishes geoscience research papers, monographs and map descriptions for Denmark, Greenland and the Arctic region. We believe that open science benefits scientists, industry and society, so we do not charge publication fees and all our articles can be freely downloaded online.</p> <p><strong>GEUS Bulletin is open for submissions to geoscientists whose research is focussed on Denmark, Greenland and the Arctic region. Read more in our <a href="">journal scope</a>.</strong></p> Peneplains and tectonics in North-East Greenland after opening of the North-East Atlantic 2021-01-25T11:58:34-08:00 Johan M. Bonow Peter Japsen <p>Elevated plateaus with deeply incised valleys characterise elevated, passive continental margins (EPCMs) in all climate zones. These features are, however, a topic of debate regarding when and how the large-scale landscapes formed. We have investigated and mapped the partly glaciated landscape of North-East Greenland (70–78°N). The area consists of crystalline basement and Palaeozoic–Mesozoic rift basins, capped by Palaeogene basalts that erupted during the northeast Atlantic break-up. Our stratigraphic landscape analysis reveals a typical EPCM dominated by two elevated erosion surfaces, extending 200 km east–west and 900 km north–south. The low-relief Upper Planation Surface (UPS; c. 2 km above sea level) cuts across basement and Palaeogene basalts, indicating that it was graded to base level defined by the Atlantic Ocean in post-basalt times and subsequently uplifted. The UPS formed prior to the deposition of mid-Miocene lavas that rest on it, south of the study area. In the interior basement terrains, the Lower Planation Surface (LPS) forms fluvial valley benches at c. 1 km above sea level, incised below the UPS. The LPS is thus younger than the UPS, which implies that it formed post mid-Miocene. Towards the coast, the valley benches merge to form a coherent surface that defines flat-topped mountains. This shows that the LPS was graded to near sea level and was subsequently uplifted. Hence, both the UPS and the LPS formed as peneplains – erosion surfaces graded to base level. The fluvial valley benches associated with the LPS further indicates that full glacial conditions were only established after the uplift of the LPS in the early Pliocene (c. 5 Ma). The uplift of the LPS led to re-exposure of a Mesozoic etch surface. We conclude that episodes of late Neogene tectonic uplift shaped the stepped landscape and elevated topography in North-East Greenland.</p> 2021-01-21T10:28:23-08:00 Copyright (c) 2021 Johan M. Bonow, Peter Japsen Middle Jurassic sandstone deposition in the Wandel Sea Basin: evidence from cardioceratid and kosmoceratid ammonites in the Mågensfjeld Formation in Kilen, North Greenland 2020-12-22T06:37:08-08:00 Peter Alsen Jussi Hovikoski Kristian Svennevig <p>Age assessments from both palynostratigraphy and macrofossil biostratigraphy of the sandstone-dominated Mågensfjeld Formation, Wandel Sea Basin, North Greenland were hitherto hampered by post-burial thermal degradation of dinoflagellate cysts and a lack of well-preserved macrofossils. The formation was previously assigned to the Upper Cretaceous based on erroneous fossil identifications. Finds of cardioceratid and kosmoceratid ammonites during recent field work now provide the first age control of the unit, demonstrating it to be of late Bajocian – late Bathonian and perhaps Callovian (Middle Jurassic) age. This makes it among the oldest Jurassic units, perhaps even Mesozoic units, recorded in Kilen, North Greenland and eastern North Greenland. Previously, the complex structural and tectonic evolution of the area was poorly understood, and the structural relation of the Mågensfjeld Formation to the surrounding Mesozoic units was a puzzle. The new age assessment simplifies the structural situation in the area significantly. Further, the inference of a large reverse fault previously required to explain the proximity of the Mågensfjeld Formation to neighbouring Jurassic units is now unnecessary. The data show that the Wandel Sea Basin was influenced by the Middle Jurassic transgression and had sufficient accommodation space for marine deposition earlier than previously thought. The unit serves as a key datapoint and analogue for possible Middle Jurassic units in adjacent offshore basins.</p> 2020-12-21T10:30:04-08:00 Copyright (c) 2020 Peter Alsen, Jussi Hovikoski, Kristian Svennevig A review of oil and gas seepage in the Nuussuaq Basin, West Greenland – implications for petroleum exploration 2020-12-09T00:48:33-08:00 Flemming G. Christiansen Jørgen A. Bojesen-Koefoed Gregers Dam Troels Laier Sara Salehi <p>The Nuussuaq Basin in West Greenland has an obvious exploration potential. Most of the critical elements are well documented, including structures that could form traps, reservoir rocks, seals and oil and gas seepage that documents petroleum generation. And yet, we still lack a full understanding of the petroleum systems, especially the distribution of mature source rocks in the subsurface and the vertical and lateral migration of petroleum into traps. A recently proposed anticlinal structural model could be very interesting for exploration if evidence of source rocks and migration pathways can be found. In this paper, we review all existing, mostly unpublished, data on gas observations from Nuussuaq. Furthermore, we present new oil and gas seepage data from the vicinity of the anticline. Occurrence of gas within a few kilometres on both sides of the mapped anticline has a strong thermogenic fingerprint, suggesting an origin from oil-prone source rocks with a relatively low thermal maturity. Petroleum was extracted from an oil-stained hyaloclastite sample collected in the Aaffarsuaq valley in 2019, close to the anticline. Biomarker analyses revealed the oil to be a variety of the previously characterised “Niaqornaarsuk type,” reported to be formed from Campanian-age source rocks. Our new analysis places the “Niaqornaarsuk type” 10 km from previously documented occurrences and further supports the existence of Campanian age deposits developed in source rock facies in the region.</p> 2020-12-04T12:38:30-08:00 Copyright (c) 2020 Flemming G. Christiansen, Jørgen A. Bojesen-Koefoed, Gregers Dam, Troels Laier, Sara Salehi Preliminary landslide mapping in Denmark indicates an underestimated geohazard 2020-11-09T00:20:11-08:00 Kristian Svennevig Gregor Lützenburg Marie K. Keiding Stig Asbjørn Schack Pedersen <p>The process of coastal erosion is well known to the public and decision-makers in Denmark; however, there is little awareness of the risks posed by larger landslides. Only a few scientific studies investigate landslides in Denmark, and as a result, the country is underrepresented in international landslide inventories. Here, we present a systematically produced preliminary landslide inventory based on digital elevation models and high-resolution orthophotos. So far, the preliminary inventory documents 3026 morphological expressions of landslides close to the coast and inland, showing that landslides are more widespread in Denmark than previously recognised. A number of these landslides are near buildings and infrastructure. This paper therefore highlights the potential for geohazardous landslides to occur in Denmark on a national scale and discusses some of the implications. Two of the major questions arising from this study are (1) how to approach potential geohazards in a country with no framework or precedence for landslide hazard and risk management and (2) how landslides and associated risk in Denmark will evolve under a changing climate.</p> 2020-11-09T00:00:00-08:00 Copyright (c) The lower Miocene flint conglomerate, Jylland, Denmark: a result of the Savian tectonic phase 2020-11-03T07:07:41-08:00 Erik Skovbjerg Rasmussen Karen Dybkjær <p>The early Miocene was an important period for the development of the eastern North Sea. Tectonism in North-West Europe resulted in uplift of the Scandinavian mountains, reactivation of salt structures, inversion of old graben structures and deposition of the most coarse-grained deposits in the Danish pre-Quaternary succession. Some of these deposits were later cemented into conglomerates. The deposits are common in the fluvial parts of the Billund Formation (Aquitanian) and the basal transgressive lag of the late Aquitanian – Burdigalian Klintinghoved Formation capping the Billund Formation. Questions remained as to the age of these deposits and what they infer about tectonic events in the region. This study reviews the geology of the flint-dominated conglomerates and presents the first dates for a sample of these unique deposits. We observe grain sizes up to 5 cm diameter. Palynological analyses place the sample as early Miocene. Some samples from the area have suggested a local source near active salt structures, associated with the uplift of the pre-Neogene sedimentary successions. We suggest that the common occurrences of flint clasts in the lower Miocene succession reveal significant erosion of Upper Cretaceous and Danian chalk, likely associated with the uplift of the Scandinavian lowlands during the Savian tectonic phase, early Miocene.</p> 2020-11-02T13:04:09-08:00 Copyright (c) 2020 Erik Skovbjerg Rasmussen, Karen Dybkjær Petrography, geochemistry and magnetic susceptibility of the Isortoq Fe-Ti-V deposit, Isortoq Giant Dykes, South Greenland 2020-09-22T03:38:44-07:00 Diogo Rosa Alessandro Sandrin Troels F.D. Nielsen Høgni Vesturklett <p>The Isortoq Giant Dykes in the Proterozoic Gardar Province, South Greenland, include the Isortoq South giant dyke and the Isortoq North giant dyke. The fine-grained Fe-Ti-V deposit hosted by the Isortoq South giant dyke, referred to as the Isortoq Fe-Ti-V deposit, is considered a good test site for the use of magnetic susceptibility for the mapping of ore grades. Here, we test this and show that the Fe, Ti and V distribution is controlled by titanomagnetite disseminated throughout fine-grained troctolite. The deposit displays a clear correlation between magnetic susceptibility and Fe, Ti and V grades in bulk samples of consecutive 2 m sections from 11 drill cores, totalling 2671 m in length. We observe that Fe, Ti and V are almost entirely hosted in titanomagnetite, which controls the magnetic susceptibility. Field measurements of the magnetic susceptibility can thus be considered as a reliable exploration tool for this type of mineralisation. We further consider the origins of the deposit by reconnaissance petrography, mineral and bulk rock chemistry of the large mass of aphanitic Fe-rich troctolite in the Isortoq South giant dyke. We suggest that the deposit may represent the base of a basanitic to trachybasaltic magma chamber, in which Fe-rich immiscible melts accumulated, crystallised and fractionated. The processes suggested here may apply to other giant dykes and intrusions of the Gardar Province.</p> 2020-08-21T14:30:58-07:00 Copyright (c) 2020 Diogo Rosa, Alessandro Sandrin, Troels Nielsen, Høgni Vesturklett Geophysics for urban mining and the first surveys in Denmark: rationale, field activity and preliminary results 2020-07-03T05:47:57-07:00 Alessandro Sandrin Aleksandar Maricak Björn H. Heincke Rune J. Clausen Lars Nielsen Jakob K. Keiding <p>Geophysical methods have been widely used in recent decades to investigate and monitor landfill sites for environmental purposes. With the advent of the circular economy, waste contained in old landfills may be considered a resource that can be developed. Since the content of old landfills is largely unknown, the occurrence and quantity of valuable materials must be investigated before embarking on any development activity. Two landfills on Sjælland, Denmark (located at Hvalsø and Avedøre) were selected for a pilot study to characterise their content. At both locations, a set of geophysical surveys is underway. Here, we present the data obtained from magnetic and 2D seismic refraction surveys. Magnetic data show various anomalies that can be interpreted as caused by iron-rich waste. At both sites, the landfill material results in generally low P-wave velocity (&lt;400 m/s), lower than those obtained for Quaternary sediments at Avedøre. The seismic velocities appear to increase in the presence of metals or by compaction with depth (&gt;550 m/s). We propose that seismic refraction can thus define the bottom of the landfill and possibly its internal structure, especially when combined with other methods.</p> 2020-07-02T12:49:46-07:00 Copyright (c) 2020 Alessandro Sandrin, Aleksandar Maricak, Björn H. Heincke, Rune J. Clausen, Lars Nielsen, Jakob K. Keiding Late Quaternary history of Lammefjorden, north-west Sjælland, Denmark 2020-07-07T04:12:20-07:00 Ole Bennike Peter Roll Jakobsen Jakob Walløe Hansen <p>Lammefjorden is a reclaimed fjord in north-west Sjælland, Denmark. Sediment cores from the area were collected to study its development after the last deglaciation, in particular the sea-level history. Late glacial and Early Holocene lake and bog deposits occur below marine deposits. Sparse late glacial fossil assemblages indicate tree-less environments with dwarf-shrub heaths. Early Holocene deposits contain remains of <em>Betula</em> sec. <em>Albae</em> sp. and <em>Pinus sylvestris</em>, which indicate open forests. The wetland flora comprised the calciphilous reed plant <em>Cladium mariscus</em> and the water plant <em>Najas marina</em>. Marine gyttja from basins is characterised by sparse benthic faunas, probably due to high sedimentation rates. In some areas, shell-rich deposits were found, with large shells of<em> Ostrea edulis</em>, indicative of high summer temperatures, high salinity and strong tidal currents. A marine shell dated to 6.7 cal. ka provides a minimum age for the marine transgression of Lammefjorden.</p> 2020-06-25T11:38:05-07:00 Copyright (c) 2020 Ole Bennike, Peter Roll Jakobsen, Jakob Walløe Hansen Semi-conventional play: definition, exploration strategy and the example of the Chalk Group in Denmark 2020-07-02T13:56:52-07:00 Alessandro Sandrin <p>Play analysis has been widely used in hydrocarbon exploration for decades with great success. In recent years, progress has also been made to describe reservoir properties of very low permeability reservoirs. However, comparatively little research has been done into play analysis for such reservoirs, which may lead to misleading estimates of their hydrocarbon potential. Here, the concept of a semi-conventional play is defined and characterised as having a reservoir of such low permeability that a hydrocarbon column can form down-dip of an effective dry trap. A new exploration approach is proposed for such plays, using the Chalk Group Play in the Danish North Sea as an example. It is suggested that together with the usual risk elements, a more detailed analysis of ‘charge’ is necessary, paying particular attention to identifying possible hydrocarbon entry points, palaeostructures and the maximum distance from these entry points that the hydrocarbons may have reached since they first entered the reservoir. The application of this novel approach for semi-conventional plays in mature basins can help unlock further resources in proximity of existing fields, and reduce the risk of failure in frontier exploration.</p> 2020-05-26T00:00:00-07:00 Copyright (c) 2020 Alessandro Sandrin Characterisation of incinerator bottom ash from a Danish waste-to-energy plant: a step towards closing the material cycle 2021-03-05T08:30:51-08:00 Rune J. Clausen Per Kalvig Jonas Nedenskov <p>The UN Sustainable Development Goal 12, regarding responsible production and consumption of raw materials, guides ongoing international efforts to enhance sustainability in all parts of the mineral sector. Of particular interest, is improving the recyclability of secondary waste streams and thereby increasing the efficiency of recycling end-of-life products. Municipal solid waste – residual waste from household and industry – constitutes one of these secondary streams. It is typically incinerated in waste-to-energy plants producing two types of waste streams that carry a raw material resource potential: incinerator bottom ash (IBA) and incinerator fly ash (IFA). IBA is of particular interest in the recycling industry, where it is commonly recycled to produce three main fractions: (i) ferrous material, (ii) non-ferrous material, and (iii) residual slag. In most cases the two metal fractions are separated further downstream in the value chain, prior to smelting. The residual, non-magnetic fraction (typically 0–45 mm) is used mainly as construction aggregate. Improvements in the efficiency of existing separation technologies are still being made, but less effort is focussed on characterising the fundamental composition and mineral resource potential of IBA. For this reason, the Urban-X project was launched by the Geological Survey of Denmark and Greenland (GEUS) to characterise the composition and resource potential of various waste streams at Amager Bakke waste-to-energy plant in Copenhagen, Denmark. This paper discusses some of the main outcomes of the Urban-X project with respect to IBA, and a full analysis of all waste streams analysed at Amager Bakke is available in Clausen&nbsp;<em>et al</em>. 2019.</p> 2019-12-20T00:00:00-08:00 Copyright (c) Review of Survey activities 2018 2021-03-05T08:31:15-08:00 Flemming G. Christiansen <p>Every four years the Geological Survey of Denmark and Greenland (GEUS) develops and implements new strategies to ensure that we are able to help meet the ever-changing challenges that face society. In 2018 these discussions were shaped by important issues like climate change and climate adaptation, and their consequences for our use of energy, minerals and water resources. As part of this strategic focus, GEUS introduced a new publication strategy in 2018 that seeks to increase our publication rate of high impact science, and to gain more visibility within the international scientific community and the media. Many different tools will be applied to make such a long-term cultural change possible, including modernisation of GEUS’ own publication series.</p> 2019-08-07T00:00:00-07:00 Copyright (c) Developing multi-sensor drones for geological mapping and mineral exploration: setup and first results from the MULSEDRO project 2021-03-05T08:31:38-08:00 Björn Heincke Robert Jackisch Ari Saartenoja Heikki Salmirinne Sönke Rapp Robert Zimmermann Markku Pirttijärvi Erik Vest Sörensen Richard Gloaguen Lisa Ek Johan Bergström Arto Karinen Sara Salehi Yuleika Madriz Maarit Middleton <p>The use of Unmanned Aerial Systems (UAS), also known as drones, is becoming increasingly important for geological applications. Thanks to lower operational costs and ease of use, UAS offer an alternative approach to aircraft-based and ground-based geoscientific measurements (Colomina &amp; Molina 2014). Magnetic and hyperspectral UAS surveys hold particular promise for mineral exploration, and several groups have recently published studies of magnetic data collected by UAS for such applications (Malehmir&nbsp;<em>et al</em>. 2017; Cunningham&nbsp;<em>et al</em>. 2018), although equivalent studies using hyperspectral data are still rare (Kirsch&nbsp;<em>et al</em>. 2018). Combining both techniques is particularly useful. Magnetic measurements play an important role in mineral exploration, since magnetisation in rocks is mainly associated with magnetite and other iron minerals, which can be used in mapping and targeting of mineral deposits (Dentith &amp; Mudge 2014). Hyperspectral imaging (HSI) is a powerful exploration and mapping technique in areas where the rock surface is well-exposed, and where geological units and mineral compositions can be estimated from spectral features of the electromagnetic spectrum in the visual and infrared range.</p> 2019-07-29T00:00:00-07:00 Copyright (c) The North Atlantic Provenance Database: an introduction 2021-03-05T08:32:49-08:00 Christian Knudsen Martin Sønderholm Tjerk Heijboer Jeppe Å. Kristensen Dag Bering <p class="p1">The amount of provenance information available for onshore and offshore sedimentary deposits in the North Atlantic Region is substantial and rapidly increasing. These data provide an improved understanding of reservoir geology (quality, diagenetic issues, regional source-to-sink relations and local stratigraphic correlations), and thereby can reduce hydrocarbon exploration risk.<span class="Apple-converted-space">&nbsp;</span>As such, the number of proprietary, industry-related and public research provenance studies has increased considerably in recent years, and the development and use of new analytical techniques has also caused a surge in the number of grains, isotopes and chemical elements analysed in each study. As a result, it is today close to impossible for the individual researcher or petroleum geologist to draw on all existing provenance data. And the vast expansion of data availability demands new and better methods to analyse and visualise large amounts of data in a systematic way</p> <p class="p1">To this end, the Geological Survey of Denmark and Greenland (GEUS) and the Norwegian Petroleum Directorate (NPD) have established a web-based database of provenance data for the North Atlantic area: the North Atlantic Provenance Database. Construction of the database was funded jointly by GEUS and NPD. Future maintenance and further development will be funded by the petroleum industry by subscription to the database.<span class="Apple-converted-space">&nbsp;</span>Here, we provide a brief introduction to the database and its future development and expansion. We highlight the current capabilities with an example from East Greenland.<span class="Apple-converted-space">&nbsp;</span></p> 2019-07-22T00:00:00-07:00 Copyright (c) Distribution of porosity-preserving microquartz coatings in sandstones, Upper Jurassic Danish Central Graben 2021-03-05T08:32:26-08:00 Margrethe T. Nielsen Rikke Weibel Jens Therkelsen Henrik Friis <p>High porosity is a key factor for good reservoir sandstones for both hydrocarbon and geothermal energy exploitation. The porosity of sandstones generally decreases with increased burial depth due to compaction and cementation. However, some sandstones in the North Sea show higher porosity than expected for their burial depth, due to the presence of micro­quartz coatings (e.g. Aase&nbsp;<em>et al</em>. 1996; Hendry &amp; Trewin 1995; Jahren &amp; Ramm 2000; Maast&nbsp;<em>et al</em>. 2011). Siliceous sponge spicules have been documented to be an internal source of silica that promotes microquartz coatings (e.g. Hendry &amp; Trewin 1995; Aase&nbsp;<em>et al</em>. 1996). Siliceous sponge spicules, the solid ‘skeleton’ of sponges, consist of opal-A and will dissolve when exposed to higher temperatures, thereby causing supersaturation of the formation water with respect to opal-CT and quartz, resulting in nucleation of numerous small (1–5 µm) quartz crystals (Williams&nbsp;<em>et al</em>. 1985; Hendry &amp; Trewin 1995). To predict reservoir quality it is important to understand the distribution of porosity-preserving microquartz in clastic deposits, and yet this is still poorly understood. To address this, our study presents petrographical analyses of cored sandstone sections from wells of various depositional environments, including<span class="Apple-converted-space">&nbsp;&nbsp;</span>back-barrier, estuarine, shoreface and gravity flows, as well as various present-day burial depths across the Danish Central Graben.&nbsp;</p> <p>&nbsp;</p> 2019-07-22T00:00:00-07:00 Copyright (c) Liverpool Land Basement High, Greenland: visualising inputs for fractured crystalline basement reservoir models 2021-03-05T08:32:02-08:00 Graham Banks Stefan Bernstein Sara Salehi Pierpaolo Guarnieri Dennis Bird Catherine Hamblett David Peacock Jon Foster <p class="p1">Basement highs are large structural features, commonly buried in sedimentary basins (Busby &amp; Azor 2012). They are of interest for natural resources exploration and research because of their ability to influence migration and entrapment of petroleum (Trice 2014) and water, and the deposition of metals (Hitzman 2005; Borg&nbsp;<em>et al</em>. 2012). Three-dimensional (3D) reservoir models (e.g. Shepherd 2009) are built to evaluate and model fluid-filled basement reservoirs (Ringrose &amp; Bentley 2015). However, subsurface data are expensive, difficult to obtain and are often widely spaced. Ideally, basement reservoir models would be constrained by rock, fracture and mineral vein data from appropriate outcrop analogues (acknowledging that subaerial basement rocks have, by definition, a different uplift history than subsurface basement). The Liverpool Land Basement High (LLBH) in Greenland is an uplifted and well-exposed basement high located between two sedimentary basins, and thus provides a valuable analogue for fractured basement-hosted mineral, oil and geothermal reservoirs.<span class="Apple-converted-space">&nbsp;</span></p> <p class="p1">The Geological Survey of Denmark and Greenland (GEUS) conducted reconnaissance work on the LLBH in 2018 to assess the quality of the exposure of basement palaeo-weathering profiles and fault-fracture networks. Here, we introduce the LLBH, the concept of fractured basement reservoir modelling, and how studying the LLBH can help enhance reservoir modelling of fractured basement. We present some of our preliminary observations of LLBH fault-fracture networks and discuss how the exposed sediment-basement features and processes might aid industry&nbsp;<span class="s1">and research in their top basement mapping activities. We propose that LLBH provides a particularly suitable analogue for industry and research to analyse: (a) multiscale fracture system connectivity, (b) fluid migration and fluid-rock reaction processes, (c) input parameters for basement reservoir modelling and (d) top basement geomorphologies and processes.</span></p> 2019-07-22T00:00:00-07:00 Copyright (c) Characterising brines in deep Mesozoic sandstone reservoirs, Denmark 2021-03-05T08:33:59-08:00 Hanne D. Holmslykke Niels H. Schovsbo Lars Kristensen Rikke Weibel Lars Henrik Nielsen <p>The Danish subsurface contains several sandstone units, which represent a large geothermal resource (Vosgerau&nbsp;<em>et al</em>. 2016). Currently, only three geothermal plants are operating in Denmark, but several exploration licences are expected to be awarded in 2019. Geothermal energy is exploited from deeply buried porous sandstones by bringing warm form­ation water (brine) to the surface, extracting the heat and returning the cooled water to the same sandstones. The reduced temperature of the brine during this process implies a risk of scaling, which may reduce reservoir permeability and hence injectivity. Predicting the chemical composition of formation waters, however, could help to reduce the risk associated with scaling in planned geothermal facilities.</p> <p class="p1">Here, we present a regional overview of the geochem­istry of brines from deep Mesozoic sandstones in the Danish Basin and North German Basin that supplements previous studies, notably by Laier (2002, 2008). The brine composition at shallow burial typically reflects the original (connate) formation water chemistry, which is determined by the original depositional environment of the sandstone, for example fluvial or marine. However, the mineralogical composition of the sandstone changes during burial, whereby some minerals may dissolve or precipitate when exposed to higher temperatures. These mineral changes are reflected in the brine composition, which typically becomes more saline with increased burial (e.g. Laier 2008; Kharaka &amp; Hanor 2003).<span class="Apple-converted-space">&nbsp;</span></p> <p class="p1">The brine chemistry reported here shows a distinct depth trend, which reflects original connate formation waters that are modified through burial diagenesis. We have classified the brines into brine types, which are shown to be related to their depositional environment, depth, geological formation and geographical domains.</p> <p class="p1">&nbsp;</p> 2019-07-17T00:00:00-07:00 Copyright (c) Comparison of ASTER and Sentinel-2 spaceborne datasets for geological mapping: a case study from North-East Greenland 2021-03-05T08:33:35-08:00 Sara Salehi Christian Mielke Christian Brogaard Pedersen Simun Dalsenni Olsen <p>Spaceborne remote sensing is a suitable tool for early mineral exploration and surveying large areas of high Arctic environment in a fast and cost-effective manner. While spaceborne data have been used widely to map geology in arid areas, similar approaches for remotely-sensed geological mapping of Arctic environments is yet to be developed. Freely available spaceborne optical data provides detailed information of high-quality that could potentially reduce resource exploration risk in remote regions. To this end, this study compares the use of two different multispectral spaceborne datasets (i.e. the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Sentinel-2) to map geological units in and around Wollaston Forland, North-East Greenland – an area rich in Jurassic and Cretaceous sedimentary rocks and important targets for offshore petroleum exploration. Multispectral image sensors simultaneously capture image data within multiple wavelength ranges (bands) across the electromagnetic spectrum. Each band is commonly described by the band number and the band wavelength centre position. Here, we identify the bands most suitable for geological mapping in an Arctic setting, using the Wollaston Forland area as an example. We compare the results obtained by processing spaceborne data with a published geological map for the area (Henriksen 2003).</p> 2019-07-17T00:00:00-07:00 Copyright (c) Mapping glacial rock flour deposits in Tasersuaq, southern West Greenland 2021-03-05T08:33:12-08:00 Ole Bennike Jørn Bo Jensen Frederik Næsby Sukstorf Minik T. Rosing <p>Global population has increased rapidly in recent decades. So far, it has been possible to feed the growing population by using more and more land for agriculture, using irrigation and artificial fertilisers and by improving the efficiency of agriculture. Recently the growth of the global agricultural area has slowed. However, the need for food will continue to grow markedly in coming years. This demand can no longer be met by using increasingly more land for agriculture, and in many areas it is not possible to increase crop production by irrigation (Wise 2013).</p> <p>Large areas in the tropics are characterised by strongly depleted soils with low concentrations of nutrients such as nitrogen, phosphorous and potassium. In such areas, the yield of crop per hectare is much lower than the theoretical yield using optimal fertilising (Ray&nbsp;<em>et al.</em>&nbsp;2013). Reducing the gap between real and potential crop productivity offers the best solution to achieve food security for the world’s rapidly growing population.</p> <p>Poor soil quality in the tropics is largely due to the rapid weathering of minerals and leaching of dissolved nutrients in the warm and humid climate. If weathered minerals are not replaced by new minerals, for example due to volcanic activity, then soil fertility continues to decline over time. Therefore, it is necessary to use increasing amounts of fertilisers to feed growing populations in the tropics. Most nutrients come from geological deposits; the only exception is nitrogen, which can be extracted from the atmosphere. Nutrients that are mined constitute a limited resource. Hence the known occurrences of phosphorous can only cover the current demand for a few decades (van Vuuren&nbsp;<em>et al.</em>&nbsp;2010).</p> <p>In recent years, investigations have been conducted to see if the productivity of nutrient-poor soils can be improved by the application of glacial rock flour from Greenland. Rock flour in southern West Greenland consists of fine-grained silt, formed by the grinding of bedrock by stones and boulders embedded in the basal part of glaciers. Preliminary results indicate that plants cultivated in soils with rock flour can achieve increased growth (M.T. Rosing, unpublished data 2019). However, the research is still in its early days and many questions remain. We do not know why adding rock flour to soil results in increased growth. Maybe the silt fraction improves the soil properties. Also we do not know if it is feasible to mine rock flour and transport it to the tropics. As a first step towards answering some of these questions, our aim here was to simply map and sample the glacial rock flour in Tasersuaq, a large proglacial lake in southern West Greenland,&nbsp;<em>c.</em>&nbsp;105 km north-east of Nuuk.</p> 2019-07-17T00:00:00-07:00 Copyright (c) Greenland ice sheet mass balance assessed by PROMICE (1995–2015) 2021-03-05T08:34:45-08:00 William Colgan Kenneth D. Mankoff Kristian K. Kjeldsen Anders A. Bjørk Jason E. Box Sebastian B. Simonsen Louise S. Sørensen S. Abbas Khan Anne M. Solgaard Rene Forsberg Henriette Skourup Lars Stenseng Steen S. Kristensen Sine M. Hvidegaard Michele Citterio Nanna Karlsson Xavier Fettweis Andreas P. Ahlstrøm Signe B. Andersen Dirk van As Robert S. Fausto <p>The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) has measured ice-sheet elevation and thickness via repeat airborne surveys circumscribing the ice sheet at an average elevation of 1708 ± 5 m (Sørensen<em>&nbsp;et al.</em>&nbsp;2018). We refer to this 5415 km survey as the ‘PROMICE perimeter’. Here, we assess ice-sheet mass balance following the input-output approach of Andersen<em>&nbsp;et al</em>. (2015). We estimate ice-sheet output, or the ice discharge across the ice-sheet grounding line, by applying downstream corrections to the ice flux across the PROMICE perimeter. We subtract this ice discharge from ice-sheet input, or the area-integrated, ice sheet surface mass balance, estimated by a regional climate model. While Andersen<em>&nbsp;et al</em>. (2015) assessed ice-sheet mass balance in 2007 and 2011, this updated input-output assessment now estimates the annual sea-level rise contribution from eighteen sub-sectors of the Greenland ice sheet over the 1995–2015 period.</p> 2019-07-08T00:00:00-07:00 Copyright (c) U-Pb dating identifies titanite precipitation in Paleogene sandstones from a volcanic terrane, East Greenland 2021-03-05T08:34:22-08:00 Rikke Weibel Tonny B. Thomsen <p>Titanite (CaTiSiO<sub>5</sub>) occurs as a rare mineral in magmatic and metamorphic rocks. It is commonly found in clastic sedimentary rocks as an accessory heavy mineral – a mineral of high density.&nbsp;Recently, U-Pb dating of single-grains of detrital titanite has been shown to be a useful tool in sedimentary provenance studies (e.g. McAteer&nbsp;<em>et al</em>. 2010; Thomsen&nbsp;<em>et al</em>. 2015). Titanite U-Pb geochronologies can add important information to constrain the sediment sources of rocks and basins, and can help date precipitation of titanite. However, there are a number of complicating factors that must be taken into consideration for reliable application of titanite U-Pb dating in provenance studies.</p> <p>First, titanite is less stable than zircon – the most commonly employed dating target. For example, in Palaeocene sediments in the North Sea, titanite rarely occurs as detrital grains at burial depths greater than 1400 m (Morton 1984). It can also show dissolution features due to weathering and burial diagenesis (e.g. Morton 1984; Turner &amp; Morton 2007). Second, titanite may precipitate during burial diagenesis, which would reflect the burial history of sediments and not their provenance. Precipitation of authigenic titanite is documented from deeply buried (i.e. at temperatures greater than 100°C) volcaniclastic sandstones and mudstones (Helmond &amp; Van de Kamp 1984; Milliken 1992) and intrusion-associated mineralisation in volcanic Permian sandstones (van Panhuys-Sigler &amp; Trewin 1990). Moreover, titanite also occurs in shallow-buried Jurassic sandstones with no volcanic affinity (Morad 1988). Thus, the formation of titanite is not necessarily linked to a volcaniclastic source, but nevertheless, the presence of volcanic material seems to promote titanite precipitation. If authigenic titanite precipitation was incorrectly identified as detrital, this would have considerable implications for provenance investigations, as apparently titanite-rich source rocks would be wrongly inferred to be present in the sediment source area. Here, we present examples from the Kangerlussuaq Basin in southern East Greenland of what appeared to be detrital titanite. However, new U-Pb dating reveals that the titanite formed authigenically, and hence contributed to the burial history, and not the provenance, of the sediments.</p> 2019-07-08T00:00:00-07:00 Copyright (c) Sea-level rise in Denmark: Bridging local reconstructions and global projections 2021-03-05T08:35:32-08:00 William Colgan Jason E. Box Sofia Ribeiro Kristian K. Kjeldsen <p>Between 1850 and 2006 global mean sea level rose by 24 ± 18 cm. It is projected to rise a further 52 ± 21 cm under the Representative Concentration Pathway (RCP) 4.5 scenario, which approximates the carbon emissions reductions of the ‘Paris Agreement’ climate pathway. It is projected to rise 74 ± 28 cm under the RCP8.5 scenario, which represents a ‘business-as-usual’ climate pathway (Box &amp; Colgan 2017). These rates of recent and future sea-level rise are faster than those reconstructed for previous warm intervals, such as the Medieval Climatic Optimum (<em>c</em>. 1000 to 1400 CE) and the Holocene Thermal Maximum (<em>c.</em>&nbsp;7000 to 3000 BCE) (Gehrels &amp; Shennan 2015). Moreover, palaeo reconstructions indicate a global sea-level sensitivity of two metres per degree of warming (Levermann&nbsp;<em>et al</em>. 2013).</p> <p>The forces driving global sea-level change are complex. The global sea-level budget includes the transfer of land ice into the ocean, thermal expansion of seawater, changes in land water storage, and changes in ocean basin volume (Church&nbsp;<em>et al</em>. 2013). At the local scale, the evolving planetary gravity due to shifting water and ice masses, shifting oceanic and atmospheric currents and persistent tectonic and glacial isostatic adjustment processes can also be important. Sea-level changes around the globe are therefore far from uniform (Jevrejeva&nbsp;<em>et al</em>. 2016).</p> <p>Here, we highlight the value of combining palaeo reconstructions of sea level, the measured tide gauge record, and projections of future sea level. This allows us to understand local sea-level changes from the recent past in the context of global projections for the near future (0 to 2100 CE). We explore the strong differences in local sea-level histories and future projections at three Danish cities: Skagen and Esbjerg, as they have contrasting glacio-isostatic adjustment histories, and Copenhagen, where we also compare local and global drivers of present-day sea-level rise based on previously published research.</p> 2019-07-01T00:00:00-07:00 Copyright (c) A multidisciplinary approach to landslide monitoring in the Arctic: Case study of the March 2018 ML 1.9 seismic event near the Karrat 2017 landslide 2021-03-05T08:35:09-08:00 Kristian Svennevig Anne Munck Solgaard Sara Salehi Trine Dahl-Jensen John Peter Merryman Boncori Tine B. Larsen Peter H. Voss <p>The landslide of 17 June 2017 at Karrat Fjord, central West Greenland, triggered a tsunami that caused four fatalities. The catastrophe highlighted the need for a better understanding of landslides in Greenland and initiated a recent nation-wide landslide screening project led by the Geological Survey of Denmark and Greenland (GEUS; see also&nbsp;<a href="">Svennevig (2019)&nbsp;this volume</a>).</p> <p>This paper describes an approach for compiling freely available data to improve GEUS’ capability to monitor active landslides in remote areas of the Arctic in near real time. Data include seismological records, space borne Synthetic Aperture Radar (SAR) data and multispectral optical satellite imagery. The workflow was developed in 2018 as part of a collaboration between GEUS and scientists from the Technical University of Denmark (DTU). This methodology provides a model through which GEUS will be able to monitor active landslides and provide relevant knowledge to the public and authorities in the event of future landslides that pose a risk to human life and infrastructure in Greenland.</p> <p>We use a minor event on 26 March 2018, near the site of the Karrat 2017 landslide, as a case study to demonstrate 1) the value of multidisciplinary approaches and 2) that the area around the landslide has continued to be periodically active since the main landslide in 2017.</p> 2019-07-01T00:00:00-07:00 Copyright (c) Update of annual calving front lines for 47 marine terminating outlet glaciers in Greenland (1999–2018) 2021-03-05T08:35:55-08:00 Jonas K. Andersen Robert S. Fausto Karina Hansen Jason E. Box Signe B. Andersen Andreas P. Ahlstrøm Dirk van As Michele Citterio William Colgan Nanna B. Karlsson Kristian K. Kjeldsen Niels J. Korsgaard Signe H. Larsen Kenneth D. Mankoff Allan Ø. Pedersen Christopher L. Shields Anne Solgaard Baptiste Vandecrux <p>The Greenland ice sheet has been losing mass in response to increased surface melting (Khan&nbsp;<em>et al</em>. 2015; van den Broeke&nbsp;<em>et al</em>. 2017) as well as discharge of ice from marine terminating outlet glaciers (van den Broeke&nbsp;<em>et al</em>. 2009; Box&nbsp;<em>et al</em>. 2018). Marine terminating outlet glaciers flow to the ocean where they lose mass by e.g. iceberg calving. Currently, the mass loss from the Greenland ice sheet is the largest Arctic contributor to global sea-level rise (van den Broeke&nbsp;<em>et al</em>. 2009, 2017; Box&nbsp;<em>et al</em>. 2018). Therefore, monitoring&nbsp;changes in the Greenland ice sheet is essential to provide policy makers with reliable data.</p> <p>There is a consensus that most&nbsp;marine terminating outlet glaciers have retreated in recent decades, and that the increased calving rates are a response to recent atmospheric and oceanic warming (e.g. Box&nbsp;<em>et al</em>. 2018; Moon&nbsp;<em>et al</em>. 2018). The rate of dynamic mass loss is determined by changes of the glacier calving front (i.e. its terminus) position, ice thickness and changes in ice flow.&nbsp;Ocean temperature and fjord circulation also influence the calving front stability by melting the glacier below the water line, thinning the ice that is in contact with water (Moon&nbsp;<em>et al</em>. 2014). Change in calving front position is therefore an important indicator for monitoring the dynamic behaviour of the upstream area of the ice sheet, which is further modulated by local topographic features and buttressing effects (Rignot &amp; Kanagaratnam 2006; Nick&nbsp;<em>et al</em>. 2009).</p> <p>The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) is dedicated to monitoring changes in the mass budget of the Greenland ice sheet, including monitoring of the calving front lines of&nbsp;marine terminating outlet glaciers. Here, we present an updated collection of annual measurements of end-of-melt-season calving front lines for 47 marine terminating outlet glaciers in Greenland between 1999 and 2018. We also present an example application of the data set, in which we estimate area changes for this group of glaciers since 1999. The Greenland calving front lines were measured from optical satellite imagery obtained from Landsat, Aster, and Sentinel-2 (Table 1). The&nbsp;<a href="" target="_blank" rel="noopener" data-externalcookie="false">PROMICE calving front product&nbsp;</a>is freely available for download as ESRI shapefiles.</p> 2019-06-26T00:00:00-07:00 Copyright (c) Climate change: Sources of uncertainty in precipitation and temperature projections for Denmark 2021-03-05T08:36:43-08:00 Ernesto Pasten-Zapata Torben O. Sonnenborg Jens Christian Refsgaard <p>Global Climate Models (GCMs) are the main tools used to assess the impacts of climate change. Due to their coarse resolution, with cells of&nbsp;<em>c</em>. 100 km × 100 km, GCMs are dynamically downscaled using Regional Climate Models (RCMs) that better incorporate the local physical features and simulate the climate of a smaller region, e.g. a country. However, RCMs tend to have systematic biases when compared with local observations, such as deviations from day-to-day measurements, and from the mean and extreme events. As a result, confidence in the model projections decreases. One way to address this is to correct the RCM output using statistical methods that relate the simulations with the observations, producing bias-corrected (BC) projections.</p> <p>Here, we present the first assessment of a previously published method to bias-correct 21 RCM projections of daily temperature and precipitation for Denmark. We assess the projected changes and sources of uncertainty. The study provides an initial assessment of the bias correction procedure applied to this set of model outputs to adjust projections of annual temperature, precipitation and potential evapotranspiration (PET). This method is expected to provide a foundation for further analysis of climate change impacts in Denmark.</p> <p>&nbsp;</p> 2019-06-24T00:00:00-07:00 Copyright (c) The channels in Storebælt, Denmark: implications of new radiocarbon ages 2021-03-05T08:36:19-08:00 Ole Bennike Niels Nørgaard-Pedersen Jørn Bo Jensen <p>The brackish water Baltic Sea and the more saline Kattegat in the north are connected by three straits, Lillebælt, Storebælt and Øresund. Storebælt (the Great Belt) is the deepest and widest of the straits. The strait is characterised by deeply incised channels that are partly filled by sediments. The water depth in major parts of Storebælt is about 20 m, though in some areas the channels are more than 50 m deep.</p> <p>The formation of the channels has been subject to discussion. Andersen (1927) suggested that the channels formed due to strong currents that are still active today or by fluvial erosion during the so-called continental period (Fastlandstiden) in the Early Holocene. At this time, the relative sea level in the region was lower than at present and a huge lake, the Ancylus Lake, which occupied the Baltic Basin, may have drained via Storebælt. Andersen dismissed the idea that the channels were formed by subglacial erosion by meltwater during the last deglaciation. More Recently, Mathiassen (1997) interpreted some of the deposits in the channels as late glacial, a viewpoint followed by Bennike&nbsp;<em>et al.</em>&nbsp;(2004). However, the age of the late glacial deposits in the channels are poorly constrained.</p> <p>The first studies of sediment cores from Storebælt were carried out by Krog (1973), Winn (1974) and Mathiassen (1997), but these studies concentrated on the Holocene development from mires to lakes to brackish and marine environments. Wiberg-Larsen&nbsp;<em>et al.</em>&nbsp;(2001) documented the presence of Early Holocene river deposits. Here we report on some new ages of macrofossils from late glacial deposits in the Storebælt channels.</p> 2019-06-24T00:00:00-07:00 Copyright (c)